The present invention relates to an improved process for batchwise or continuous isomerization of cis-2-pentenenitrile to 3-pentenenitriles in the presence of tertiary amines of the formula I as catalysts.
WO-A-05/73176 discloses isomerizing cis-2-pentenenitrile to 3-pentenenitriles with the aid of homogeneously dissolved amines as catalysts, selected from the group of C1- to C20-mono- and -diamines.
U.S. Pat. No. 5,070,202 discloses that cis-2-pentenenitrile forms Michael adducts with primary and secondary amines at temperatures of 20 to 200° C.
A disadvantage of these isomerizations is that Michael adducts form from cis-2-pentenenitrile and the amines mentioned as catalysts.
WO 2011/124610 also already discloses using tertiary amines as catalysts for the isomerization of cis-2-pentenenitrile to 3-pentenenitriles. WO 2011/124610 teaches that the use of triethylamine as a catalyst amounts to a conversion of cis-2-pentenenitrile to 3-pentenenitriles of only 13%.